#!/bin/ksh
#This shellscript is ip_receiver.
#Split the standard input into separate files for each IP address and protocol.
#The names of the files are /tmp/$$.$ip_address.$protocol
#Then feed each file to either tcp_receiver or udp_receiver.
#Sample use: tcp_receiver dir0 dir1 dir2

if [[ $# -le 0 ]]
then
	echo $0: needs directory names as command line arguments 1>&2
	exit 1
fi

cat > /tmp/$$

while [[ -s /tmp/$$ ]]
do
	#Read the three-byte header of the IP datagram.
	length=`chopoff 1 /tmp/$$`
	protocol=`chopoff 1 /tmp/$$`
	ip_address=`chopoff 1 /tmp/$$`

	#Read the TCP segment that the IP datagram contains.
	chopoff $((length - 3)) /tmp/$$ >> /tmp/$$.$ip_address.$protocol
done

rm /tmp/$$

for ((ip_address=0; ip_address < 10; ++ip_address)) {
	for ((protocol=1; protocol <= 2; ++protocol)) {
		if [[ -s /tmp/$$.$ip_address.$protocol ]]
		then
			if [[ $protocol -eq 1 ]]
			then
				tcp_receiver $1 < /tmp/$$.$ip_address.$protocol
			elif [[ $protocol -eq 2 ]]
			then
				udp_receiver $1 < /tmp/$$.$ip_address.$protocol
			fi
			rm /tmp/$$.$ip_address.$protocol
		fi
	}

	if [[ $# -le 1 ]]
	then
		break
	fi

	shift   #Let $1 be the next directory given as a command line argument.
}

exit 0